<template>
    <!-- v-show根据total的数量决定是否显示底部组件 -->
    <div class="todo-footer" v-show="total">
        <label>
            <!-- <input type="checkbox" :checked="isAll" @change="checkAll"/> -->
            <input type="checkbox" v-model="isAll"/>
        </label>
        <span>
            <span>已完成{{ completedTodo }}</span> / 全部{{ total }}
        </span>
        <button class="btn btn-danger" @click="clearAllCompleted">清除已完成任务</button>
    </div>
</template>

<script>
export default {
    name: 'MyFooter',
    props: ['todoObjList','checkAllTodo','clearAllCompleted'],
    data() {
        return {
            
        }
    },
    computed: {
        completedTodo() {
            // 计算出已经完成的todo的数量
            return this.todoObjList.reduce((pre, todo) => pre + (todo.completed ? 1 : 0), 0)
        },
        total() {
            // 计算出所有的todo的数量
            return this.todoObjList.length
        },
        isAll: {
            get(){
                // 判断是否所有的todo都完成了
                return this.completedTodo === this.total && this.total > 0
            },
            set(value){
                // 通过修改父组件传递过来的数据，实现全选or全不选
                this.checkAllTodo(value)
            }

        }
    },
    methods: {
        checkAll(e) {
            // 实现全选or全不选
            console.log(e.target.checked)
            this.checkAllTodo(e.target.checked)
        },
    }
}
</script>

<style scoped>
/*footer*/
.todo-footer {
    height: 40px;
    line-height: 40px;
    padding-left: 6px;
    margin-top: 5px;
}

.todo-footer label {
    display: inline-block;
    margin-right: 20px;
    cursor: pointer;
}

.todo-footer label input {
    position: relative;
    top: -1px;
    vertical-align: middle;
    margin-right: 5px;
}

.todo-footer button {
    float: right;
    margin-top: 5px;
}
</style>